TWI720150B - Fiber reinforced resin molding material and manufacturing method thereof - Google Patents

Abstract

A fiber-reinforced resin molding material and a manufacturing method thereof. The fiber-reinforced resin molding material is a fiber-reinforced resin molding material comprising at least a bundle of discontinuous reinforcing fibers [A] and a matrix resin [M], and is characterized by: bundles The shaped aggregate [A] is a partially split fiber bundle formed by alternately forming a splitting treatment section and an unsplit treatment section that are split into a plurality of bundles along the longitudinal direction of a fiber bundle including a plurality of single yarns, The cutting is performed at an angle θ (0°<θ<90°) relative to the longitudinal direction of the fiber bundle. By having a bundle of specific discontinuous reinforcing fibers [A] formed by cutting part of the split fiber bundles obliquely with respect to the longitudinal direction, it can achieve extremely high mechanical properties when forming a molded product, and at the same time The deviation can be suppressed to be small.

Description

Fiber reinforced resin molding material and manufacturing method thereof

The present invention relates to a fiber-reinforced resin molding material containing a bundle of discontinuous reinforcing fibers, particularly a bundle of discontinuous reinforcing fibers of a specific form and a matrix resin, and a method for manufacturing the same.

Known is a fiber-reinforced resin molding material that uses a bundle of discontinuous reinforcing fibers (e.g., carbon fibers) (hereinafter also referred to as fiber bundles) and a matrix resin (e.g., thermosetting resin or thermoplastic resin), A technique of forming a molded body of a desired shape by heating and pressure forming (for example, Patent Documents 1 to 5). In the conventional fiber-reinforced resin molding material as described above, when fiber bundles in the fiber-reinforced resin molding material are formed of predetermined strands, fiber bundles with a predetermined number of single yarns are usually included. Among the molding materials, the fluidity during molding is good, but the mechanical properties of the molded product tend to be poor.

For example, Patent Document 1 discloses that the number of filaments of chopped fiber bundles in a molding material is defined as a molding material in the range of 10,000 to 700,000. As in the aforementioned molding material, the fiber bundle has a large number of filaments. Therefore, the reinforcing fiber and the resin can efficiently move in the form of the fiber bundle during molding, so excellent fluidity can be obtained. Regarding the molded product after molding using the molding material, when the molded product breaks, there is a high possibility of stress concentration in the fiber bundle end portion of the molded product, and it is not suitable for the molding of molded products that require high mechanical properties. .

On the other hand, for example, Patent Document 2 discloses a fiber-reinforced resin using fiber bundles divided so that the number of single yarns becomes 100 or less. However, compared with the form disclosed in Patent Document 1, the fiber bundle The number of single yarns in the molded product is very small. Therefore, in the molded product, the reinforcing fiber is well dispersed, and the possibility of stress concentration at the end of the fiber bundle in the molded product is reduced, and the mechanical properties of the molded product are improved. On the other hand, At the time of molding, there remains the possibility that the expected high fluidity cannot be obtained.

[Prior Technical Literature] [Patent Literature]

[Patent Document 1] JP 2013-202890 A

[Patent Document 2] JP 2008-174605 A

[Patent Document 3] JP 2009-191116 A

[Patent Document 4] JP 2010-163536 A

[Patent Document 5] WO2014/021315 Publication

As mentioned above, a fiber-reinforced resin molding material that uses fiber bundles with a relatively large number of single yarns has good production efficiency and tends to obtain excellent fluidity during molding, but the mechanical properties of molded products tend to be poor; The opposite is true for fiber-reinforced resin molding materials for fiber bundles with a relatively small number of yarns. Although the molded product has excellent mechanical properties, there is flow during molding. Tendency to improve sex.

Focusing on the above-mentioned tendency of the prior art, although the application is still at an undisclosed stage, the applicant in this case first proposed a fiber-reinforced resin molding material, which is at least a bundle of discontinuous reinforcing fibers and a matrix resin The fiber-reinforced resin molding material, wherein the bundle-like assembly system of the aforementioned reinforcing fibers contains in a predetermined ratio: the strands of continuous reinforcing fibers are cut to form reinforcement after the strands of continuous reinforcing fibers are completely divided into multiple bundles. Fiber assembly A; and both reinforced fiber assembly B including uncut fiber parts that have not been subjected to the aforementioned splitting treatment or/and the aforementioned splitting treatment is insufficient (PCT/JP2015/074736). According to this proposal, it is possible to have both good fluidity during molding and excellent mechanical properties of the molded product in a well-balanced manner.

However, compared with the fiber-reinforced resin molding material previously proposed by the applicant in this case, it is required that the molded product has higher mechanical properties (strength and elastic coefficient) and its deviation is further reduced.

Therefore, the subject of the present invention is to provide a fiber-reinforced resin molding material with higher mechanical properties (strength, elastic modulus) and lower deviation than the fiber-reinforced resin molding material proposed by the applicant in this case, in view of the above-mentioned needs. The fiber-reinforced resin molding material, and its manufacturing method.

In order to solve the above-mentioned problems, the fiber-reinforced resin molding material of the present invention is a fiber-reinforced resin molding material comprising at least a bundled aggregate of discontinuous reinforcing fibers [A] and a matrix resin [M], and is characterized by the aforementioned bundled aggregate [A] Contains: a partial split fiber bundle formed by alternately forming a splitting treatment section and an unsplit treatment section that are split into a plurality of bundles along the longitudinal direction of a fiber bundle containing a plurality of single yarns, to face each other When cutting the fiber bundle at an angle θ (0°<θ<90°) in the longitudinal direction of the fiber bundle.

In the fiber-reinforced resin molding material of the present invention as described above, the bundle-like aggregate [A] of discontinuous reinforcing fibers includes: a partially divided fiber bundle formed by alternately forming a fiber splitting treatment section and a non-fibering treatment section It is inclined with respect to the longitudinal direction of the fiber bundle, that is, it is formed by cutting at an angle θ (0°<θ<90°) with respect to the longitudinal direction of the fiber bundle. That is, in the aforementioned fiber-reinforced resin molding material first proposed by the applicant of the present application, the bundle-like aggregate [A] of discontinuous reinforcing fibers is formed by cutting in a direction orthogonal to the longitudinal direction of the fiber bundle; but In the present invention, in particular, the partially split fiber bundle formed by alternately forming the splitting treatment section and the unsplit treatment section is formed by cutting obliquely with respect to the longitudinal direction of the fiber bundle. By cutting obliquely with respect to the longitudinal direction of the fiber bundle, the cut surface can extend through the splitting treatment section and the unsplit treatment section, thereby making it particularly easy to form the end of the formed bundle-shaped assembly [A] , A shape that does not easily concentrate stress in the molded product (various examples will be described later); in addition, the fiber bundle of the reinforced fiber assembly B of the previous application (PCT/JP2015/074736) can be further reduced in width . As a result, the molded product can exhibit higher mechanical properties (strength, elastic coefficient) and further reduce the deviation of its mechanical properties. Regarding the good fluidity during molding, it can be ensured by cutting a part of the split fiber bundle into a bundle of discontinuous reinforcing fibers [A].

In the above-mentioned fiber-reinforced resin molding material of the present invention, in the above-mentioned partially divided fiber bundle, at least one of the above-mentioned fiber-dividing locations At least one end of the treatment zone forms the entangled part where the single yarn is entangled and/or the entangled accumulation part accumulated by the entangled part.

In addition, in the fiber-reinforced resin molding material of the present invention, the bundle-like aggregate [A] may be a form of an aggregate including at least one of the following: a fiber-divided bundle aggregate divided into an arbitrary number of bundles by a fiber splitting process [a]; A combined bundle assembly in which the single yarns of the fiber bundle are combined with each other by the above-mentioned undivided treatment section, and/or the above-mentioned entangled part, and/or the above-mentioned entangled accumulation part [b]; and the above-mentioned undivided The fiber processing section, and/or the entangled portion, and/or the entangled accumulation portion intersects the cutting surface when the partial fiber bundle is cut, and in the intersection, the single yarns of the fiber bundle are combined with each other The combined cutting aggregate to be cut [c]. In this aspect, in the bundle assembly [A], the content of the bound bundle assembly [b] is preferably in the range of 0 to 15%. That is, the binding bundle assembly [b] may not be included, and when it is included, it is preferable to suppress the content rate to not more than 15%.

The present invention also provides a method for manufacturing a fiber-reinforced resin molding material as described above. That is, the method of manufacturing a fiber-reinforced resin molding material of the present invention includes: a method of manufacturing the fiber-reinforced resin molding material as described above, characterized in that when the bundle assembly [A] is obtained, the following The partial fiber splitting fiber bundle is cut in the manner of the formula (1).

W. cosθ/D≧3． . . (1)

W: The width of the fiber bundle when cutting part of the split fiber bundle

D: Interval between the cutting planes of the bundled aggregate [A]

In the method of manufacturing a fiber-reinforced resin molding material of the present invention, it is preferable to perform a widening process on the partially-divided fiber bundle at any time before cutting the partially-divided fiber bundle. This widening treatment can be performed before and after the formation of any partial fiber bundles as long as the partial fiber bundles are cut. For example, the widening treatment can be performed at the same time as the partial fiber bundles are formed to form the so-called Widening ‧ part of the split fiber bundle; it can also be expanded immediately before cutting the part of the split fiber bundle, and continuously introduced to the cutting step.

According to the fiber-reinforced resin molding material and the manufacturing method of the fiber-reinforced resin molding material of the present invention, by having a partially split fiber bundle formed by alternately forming a splitting treatment section and an unsplit treatment section, the fiber bundle is inclined with respect to the longitudinal direction of the fiber bundle. The bundled aggregate [A] of the specific discontinuous reinforced fiber formed by cutting can realize extremely high mechanical properties (strength, elastic coefficient) when it becomes a molded product, and at the same time, it can suppress the deviation of the mechanical properties to a small amount. .

1, 17, 31, 41, 51, 61, 71, 81, 91‧‧‧Partial fiber bundle

2, 13, 15, 23, 32, 42, 64, 74‧‧‧ Fiber splitting processing section

3, 14, 16, 28, 33, 52, 62, 72, 82‧‧‧Undivided fiber processing section

4‧‧‧Cutting knife

5‧‧‧ Bundle assembly [A]

11, 25, 63‧‧‧Interlacing part

12, 26, 73‧‧‧Entanglement accumulation part

20‧‧‧Fiber Bundle

21‧‧‧ Splitting means

22‧‧‧Protrusion

24‧‧‧Contact

27‧‧‧Fuzz accumulation

34, 35, 43, 53, 65, 75, 83、92‧‧‧cut surface

36、37‧‧‧ Bundle aggregates

100‧‧‧The winding direction of the bobbin

101‧‧‧Drawing direction of fiber bundle

102‧‧‧Untwisting of fiber bundle

103‧‧‧Contains untwisted partial fiber bundles

Fig. 1 is a schematic perspective view showing a part of the split fiber bundle of the present invention and its cutting.

Fig. 2 is a schematic plan view of a fiber bundle showing an example of a form of a partially divided fiber bundle of the present invention.

[Fig. 3] Fig. 3 is a schematic plan view of a fiber bundle showing another example of the partially divided fiber bundle of the present invention.

Fig. 4 is a schematic plan view of a fiber bundle showing still another example of the partially divided fiber bundle of the present invention.

[Fig. 5] is a schematic plan view (A) and a schematic side view (B) showing an example of a method for producing a partially divided fiber bundle of the present invention.

Fig. 6 is a schematic plan view of a part of the split fiber bundle showing the basic technical idea of the oblique cutting of the present invention.

[Fig. 7] A schematic plan view of a partial fiber bundle showing an example of orthogonal cutting.

[Fig. 8] is a schematic plan view showing an example of the method of producing the fiber splitting bundle assembly [a] of the present invention.

[Fig. 9] is a schematic plan view showing an example of the method of manufacturing the combined bundle assembly [b] of the present invention.

[Fig. 10] is a schematic plan view showing another example of the method of manufacturing the combined bundle assembly [b] of the present invention.

[Fig. 11] is a schematic plan view showing still another example of the method of manufacturing the combined bundle assembly [b] of the present invention.

[Fig. 12] is a schematic plan view showing an example of the method of producing the combined cutting assembly [c] of the present invention.

Fig. 13 is a schematic plan view for explaining the formula (1) of the present invention.

Fig. 14 is a schematic perspective view showing an example of the form of an inside pull method of the present invention.

[The form of implementing the invention]

Hereinafter, the present invention will be described in detail with reference to the drawings, together with the embodiments.

First, in FIG. 1, the partial split fiber bundle formed by alternately forming a splitting treatment section and an unsplit treatment section that are split into a plurality of bundles along the longitudinal direction of a fiber bundle containing a plurality of single yarns and its cutting Be explained. As shown in Fig. 1, the partial split fiber bundle 1 formed by the splitting treatment section 2 and the unsplit treatment section 3 alternately formed along the longitudinal direction of the fiber bundle is moved in the direction A, and the fiber bundle is removed by the cutter 4 1 Cut in a direction transverse to the fiber bundle 1 to form a bundle of discontinuous reinforcing fibers [A]5. At this time, the cutting is performed at an angle θ relative to the longitudinal direction of the fiber bundle, but the cutting angle θ is defined as cutting in the oblique direction of 0°<θ<90° in the present invention; In the fiber-reinforced resin molding material, the direction is perpendicular to the longitudinal direction of the fiber bundle (θ=90°). The preferred range of the angle θ in the present invention is 0°<θ<45°, and more preferably 5°<θ<30°. In this range, it is possible to achieve both the display of high mechanical properties and low deviation, and the high handling ability of suppressing cutting error and being able to cut at a desired angle.

The above-mentioned partial split fiber bundle 1 before cutting basically has a form in which the split treatment section 2 and the unsplit treatment section 3 are alternately formed along the longitudinal direction of the fiber bundle as shown in FIG. 1, but as shown in the figure 2 or FIG. 3, it is also possible to use an entanglement portion 11 in which single yarn entangles are formed at at least one end of at least one fiber splitting treatment section 2, and/or an entanglement accumulation portion 12 formed by accumulating the entanglement portion The form.

In addition, as shown in FIG. 4, the partially split fiber bundle of the present invention also includes: a form including a split treatment zone 13 and an unsplit treatment zone 14 alternately formed along the longitudinal direction of the fiber bundle, and split fibers The processing section 15 and the undivided processing section 16 are alternately formed along the long side direction of the fiber bundle, and the fiber splitting processing section 15 on one side spans the other undivided processing section 14 Partially divided fiber bundles 17 in the form of the form.

The partially divided fiber bundle of the present invention as described above is not particularly limited, and is formed as shown in FIG. 5, for example. Fig. 5 is (A) a schematic plan view and (B) a schematic side view showing an example of piercing a fiber splitting means 21 into the moving fiber bundle 20. The fiber bundle movement direction A (arrow) in the figure is the longitudinal direction of the fiber bundle 20, and shows that the fiber bundle 20 is continuously supplied from a fiber bundle supply device not shown. The fiber splitting means 21 includes a protruding portion 22 having a protruding shape that easily penetrates the fiber bundle 20 and penetrates the moving fiber bundle 20 to generate a fiber splitting treatment section 23 slightly parallel to the longitudinal direction of the fiber bundle 20. It is also possible to use multiple fiber splitting means 21 at the same time according to the number of fiber bundles to be split. The plurality of fiber splitting means 21 can be arranged in parallel, alternately, shifted in phase, etc., and the plurality of protrusions 22 can be arbitrarily arranged.

When the fiber bundle 20 containing a plurality of single yarns is divided into a smaller number of fiber splitting bundles by the fiber splitting means 21, the plurality of single yarns are not substantially assembled in the fiber bundle 20, and the single yarns are classified as single yarns. Since there are many entangled parts, the entanglement part 25 of the single yarn entanglement may be formed in the vicinity of the contact part 24 in the fiber splitting process. Here, the formation of the entanglement portion 25 may include, for example, the entanglement of the single yarns pre-existing in the fiber splitting treatment section and the case where they are formed on (moved to) the contact portion 24 by the fiber splitting means 21; or borrowed The case where the single yarn entangled aggregate is newly formed (manufactured) by the fiber splitting means 21, etc.

After the fiber splitting treatment section 23 is generated in an arbitrary range, the fiber splitting means 21 is removed from the fiber bundle 20. By this pulling-out, a fiber splitting treatment section 23 to which a fiber splitting process is performed is generated, and at the same time, an entanglement accumulation portion 26 accumulated by the entanglement portion 25 is generated. In addition, the fluff generated from the fiber bundle in the fiber splitting process may be generated as a pile pile 27 in the vicinity of the entanglement accumulation portion 26 during the fiber splitting process.

Then, by piercing the fiber splitting means 21 into the fiber bundle 20 again, And the undivided processing section 28 is generated.

As long as the fiber bundle of the reinforcing fiber used in the present invention is a fiber bundle containing a plurality of single yarns, the type of fiber is not particularly limited. Among them, it is preferably at least one selected from the group consisting of carbon fibers, aromatic polyamide fibers, and glass fibers. These may be used alone, or two or more of them may be used in combination. Among them, carbon fiber is particularly suitable because it can provide a composite material that is lightweight and excellent in strength. The carbon fiber may be either PAN-based or pitch-based, and its average fiber diameter is preferably 3-12 μm, more preferably 6-9 μm.

In the case of carbon fiber, a fiber bundle of about 3000 to 60000 single yarn bundles containing continuous fibers is usually supplied as a winding body (package) wound on a bobbin. Although the fiber bundle is preferably untwisted, twisted strands can also be used, and it can be applied to the present invention even if it is twisted during conveyance. There is no limit to the number of single yarns. When the so-called large tow with a large number of single yarns is used, the price per unit weight of the fiber bundle is cheaper. Therefore, the more single yarns, the more the cost of the final product can be reduced. good. In addition, as a large yarn bundle, a form of so-called twisted yarn in which fiber bundles are gathered into one bundle and wound up can also be used.

When using the above-mentioned reinforcing fiber, for the purpose of improving adhesion with the matrix resin [M], etc., it is preferable to perform surface treatment. As surface treatment methods, there are electrolytic treatment, ozone treatment, ultraviolet treatment, and the like. In addition, a sizing agent may be provided for the purpose of preventing the fluffing of the reinforced fiber, improving the astringency of the fiber bundle, and improving the adhesion with the matrix resin [M]. The sizing agent is not particularly limited, but compounds having functional groups such as epoxy groups, urethane groups, amino groups, and carboxyl groups can be used, and These can also use 1 type or 2 or more types together.

The fiber bundle used in the present invention is preferably in a pre-assembled state. Here, the state of pre-bundling refers to, for example, the state of the bundle caused by the entanglement of the single yarns constituting the fiber bundle, or the state of bundle caused by the sizing agent applied to the fiber bundle, in the manufacturing process of the fiber bundle. The state of bunching caused by the twists contained in it.

Next, in FIG. 6, the basic technical idea of the present invention using the oblique cutting of the partial fiber bundles is compared with the case of FIG. 7 using the orthogonal cutting of the partial fiber bundles, and will be described at the same time. In FIGS. 6 and 7, 31 denotes a splitting treatment section 32 that splits into a plurality of bundles along the longitudinal direction of a fiber bundle including a plurality of single yarns, and an unsplit treatment section including the aforementioned entangled portion, etc. 33 Partially divided fiber bundles formed by alternately forming. In FIG. 7, the cut surface 35 with respect to the partial split fiber bundle 31 is set to a direction (90° direction) orthogonal to the longitudinal direction XX of the fiber bundle; in contrast, in the present invention, relative The angle θ of the cut surface 34 in the longitudinal direction XX of the fiber bundle is the angle θ in the oblique direction (0°<θ<90°).

Then, if the matrix resin [M] is burned out from the molded article, and only the bundled aggregate [A] of the discontinuous reinforcing fibers is observed as a plan view, it becomes, for example, the discontinuous reinforcing fibers as illustrated on the right side of Fig. 6 and Fig. 7 Bundle-shaped assembly distribution map; wherein the molded product will include the fiber-reinforced resin molding material of the fiber-reinforced resin molding material of the discontinuous reinforced fiber obtained by cutting as described above [A] and the matrix resin [M] randomly Disperse and heat and press to form. In the distribution diagram of FIG. 7, the ends of the fiber bundle in the longitudinal direction are relatively wide and formed by cutting on both sides of the undivided processing section 33 mainly including the entangled portion and the like on the cutting surface 35. square The bundle-shaped aggregate 36 formed at the end extending in the orthogonal direction remains directly in the same form as the original form. The end portion of the bundle-shaped assembly 36 is likely to cause stress concentration as described above, which may cause the degradation of the mechanical properties of the molded product or the deviation thereof. In contrast to the foregoing, in the distribution diagram of FIG. 6, there is no bundle-like aggregate 36 in a form that easily causes stress concentration as described above. For example, it is formed by oblique cutting including an undivided section 33 including entangled parts. In the bundle-shaped aggregate 37, the width is relatively narrow and the width becomes narrower toward the end, and the bundle-shaped aggregate does not have the shape of the bundle-shaped aggregate 36 at the end that tends to cause stress concentration. Therefore, the mechanical properties of the molded product can be improved, or the deviation of the mechanical properties can be reduced.

The bundle-like aggregate [A] of discontinuous reinforcing fibers formed as described above, for example, may be in the form of an aggregate including at least one of the following: a split fiber bundle aggregate divided into an arbitrary number of bundles by fiber splitting treatment [a]; A combined bundle assembly in which the single yarns of the fiber bundle are combined with each other through the undivided treatment section, and/or the entangled part, and/or the entangled accumulation section [b]; and the undivided treatment section, And/or the entangled part, and/or the entangled accumulation part intersects the cutting surface when the fiber bundle is split by cutting the part, and in the intersection part, the bonding of the single yarns of the fiber bundle is cut. c].

The above-mentioned fiber splitting bundle assembly [a] is, for example, as shown in FIG. The cutting surface 43 inclined with respect to the longitudinal direction of the fiber bundle is cut to form a small width and a predetermined length. Any number of split fiber bundle assemblies [a].

Taking the above-mentioned combined bundle assembly [b] as an example, the combined bundle assembly [b] is, for example, as shown in FIG. θ (0°<θ<90°) is cut on a cutting surface 53 that is inclined with respect to the longitudinal direction of the fiber bundle to form a bonded bundle assembly that is dented at the end of the fiber bundle in the longitudinal direction. [b]. Alternatively, the bonded bundle assembly [b] is, for example, as shown in FIG. 10, by the undivided processing section 62 spanning a part of the fiber bundle 61 and the splitting processing section 64 having the entangled portion 63 at the end, Cut with a cutting angle θ (0°<θ<90°) on a cutting surface 65 that is inclined with respect to the longitudinal direction of the fiber bundle to form a deep dent such as a deep dent at the end of the fiber bundle in the longitudinal direction. A combined bundle assembly having an entangled portion 63 [b]. Alternatively, the bonded bundle assembly [b] is, for example, as shown in FIG. 11, the undivided processing section 72 spanning a part of the fiber bundle 71 and the splitting processing section 74 having the entanglement accumulation portion 73 at the end , Cutting at a cutting angle θ (0°<θ<90°) on a cutting surface 75 that is inclined with respect to the longitudinal direction of the fiber bundle to form a deep dent such as a deep dent at the end of the fiber bundle in the longitudinal direction It has a combined bundle assembly with an entanglement accumulation portion 73 [b].

In addition, the above-mentioned combined cutting assembly [c] is, for example, as shown in FIG. 12, by partially dividing the fiber bundle 81 mainly including the undivided treatment section 82 or by spreading the undivided treatment section 82 across the entire length. In an oblique cross-cut method, cutting is performed on a cutting surface 83 that is inclined with respect to the longitudinal direction of the fiber bundle at a cutting angle θ (0°<θ<90°), and the average fiber bundle length is relatively long and has a small width. The width of the ends in the longitudinal direction is further reduced, and the cutting assembly is combined [c]. In the example in the figure, the undivided fiber processing section 82 intersects the cutting surface 83 when the partial fiber bundle 81 is cut, and in this intersection, the bonding of the single yarns of the fiber bundle 81 is cut.

Furthermore, in the above-mentioned combined cutting aggregate [c], since the average fiber bundle length becomes relatively long, when the fiber bundle is cut, or when the aggregate is dispersed, fiber bundles are naturally generated in the undivided processing section. It breaks and forms an aggregate with a smaller number of single yarns. In the present invention, the small bundled aggregate as described above is also included in the above-mentioned bound cleavage aggregate [c].

The bundle-like aggregate [A] of discontinuous reinforcing fibers may be an aggregate including at least one of the above-mentioned split fiber bundle aggregate [a], combined bundle aggregate [b], and combined cut aggregate [c] The form of the body. In the above-mentioned bundle assembly [A], from the viewpoint of exhibiting more excellent mechanical properties and low deviation, it is preferable that the content of the above-mentioned bundle assembly [b] is in the range of 0 to 15%. Here, in the present invention, the content rate refers to the frequency ratio of the combined bundle aggregate [b] occupied in the bundle aggregate [A]. That is, if the total number of bundles [A] is defined as N(A), and the number of bundles [b] contained therein is defined as N(b), then by The formula (2) shows.

{N(b)/N(A)}×100‧‧‧(2)

In the present invention, when manufacturing a fiber-reinforced resin molding material containing the above-mentioned bundle-shaped assembly [A], it is preferable that when the above-mentioned bundle-shaped assembly [A] is obtained, the following formula (1) is satisfied Way to cut part of the split fiber bundles.

W‧cosθ/D≧3‧‧‧(1)

W: The width of the fiber bundle when cutting part of the split fiber bundle

D: Interval between the cutting planes of the bundled aggregate [A]

For example, as shown in Fig. 13, if the cutting angle is set to θ, the width of the fiber bundle when a part of the split fiber bundle 91 is cut is set to W, and the interval between the cutting surfaces 92 is set to D, the side xy of △xyz The length t becomes t=D/cosθ, and if the number W/t cut by the cutting surface in the width direction of the fiber bundle W/t is preferably set as W/t≧3, then according to the above formula, the above formula (1) holds . By cutting part of the split fiber bundles in a manner that satisfies the aforementioned formula (1), the aforementioned combined cutting assembly [c] is effectively narrowed to promote the improvement of mechanical properties, which is preferable.

From this formula (1), it can be seen that it is effective to increase W (expand the width of the fiber bundle) in order to finely cut the bonded assembly [b]. At this time, by increasing W, the thickness of the bundled aggregate [A] obtained by cutting becomes thinner, so in the molded product, the stress concentration at the end of the bundled aggregate [A] can be relieved or the bundle can be lifted. The uniformity of the distribution of the morphological aggregate [A] and the matrix resin is also preferable from the viewpoint of making it easy to exhibit excellent mechanical properties. However, if the value of W is too large, the bundling force between the single yarns constituting the fiber bundle is reduced, and when a part of the split fiber bundle is cut, the shape of the bundle assembly cannot be maintained, and single yarn breakage is likely to occur. In addition, there is a case where the fluidity of the aforementioned fiber-reinforced resin molding material decreases during molding. Therefore, W is preferably in the range of 5mm≦W≦100mm, and more preferably 5mm≦W≦50mm.

In addition, the cutting angle θ (0°<θ<90°) may be reduced. However, it has its limits from the viewpoint of beam shape retention or handling. In addition, in order to satisfy the above-mentioned formula (1), the interval D of the cut planes can also be controlled, but the fiber length may fluctuate. Therefore, in order to be able to cut to the target fiber length, it is basically better to set the D system to a fixed value in advance.

In the manufacturing method of the fiber-reinforced resin molding material of the present invention, it is preferable that when the bundle-shaped assembly [A] is obtained, part of the divided fiber bundles are wound up in an inwardly drawn manner and subjected to the cutting step. In the present invention, the internal drawing method is different from the yarn tube that winds the fiber bundle on the core (generally, a paper tube is used). The yarn tube is set on the creel and the fiber bundle ends from the outside of the yarn tube. The method of unwinding the fiber bundle; it refers to removing the core of the bobbin. As shown in Figure 14, the end of the fiber bundle existing on the inside of the bobbin is placed in a state perpendicular to the winding direction 100 of the bobbin. In the winding direction of the bobbin, it is drawn out vertically.

According to the above-mentioned internal drawing method, when a part of the split fiber bundle is supplied to the cutting step, the fiber bundle on the outer side of the bobbin and the fiber bundle on the inner side of the bobbin of the other bobbin are also removed in advance. Twisting at the end allows continuous cutting processing for a long time, which is preferable. In particular, the aforementioned internal drawing method can perform twisting operations in parallel with the cutting process, which can improve productivity, and is therefore preferred. In addition, when the fiber bundle is rolled out, the rolled fiber bundle no longer has friction with the bobbin when it passes over the bobbin. Therefore, it is also preferable from the viewpoint that the generation of friction fluff can be suppressed.

On the other hand, the aforementioned internal drawing method is perpendicular to the direction in which the fiber bundle is wound (the fiber bundle is pulled out direction 101), and therefore, untwisting 102 may occur in the fiber bundle. If cutting the partially split fiber bundle 103 that includes such untwisting, depending on the twisting method, the fiber length of the obtained bundle-like aggregate [A] becomes uneven, and the cut surface of the partially split fiber bundle The case where the straight line cannot be formed is not at a level that impairs the effect of the present invention, and it can be handled substantially the same as cutting a fiber bundle without twisting.

As mentioned above, according to the present invention, by having the fiber splitting treatment Partially divided fiber bundles formed by alternating sections and undivided sections can be realized as a bundle of specific discontinuous reinforced fiber bundles [A] formed by oblique cutting with respect to the longitudinal direction of the fiber bundle. It has extremely high mechanical properties (strength, elastic modulus) when molded products, and at the same time, the deviation of the mechanical properties can be suppressed to be small.

[Example]

Next, examples and comparative examples of the present invention will be described. Furthermore, the present invention is not limited to this embodiment or comparative example.

[Used raw materials]

Fiber bundle [A-1]:

A continuous carbon fiber bundle (made by Toray (stock), "TORAYCA (registered trademark)" T700S-12K-50-E) with a fiber diameter of 7μm, a tensile modulus of 230 GPa, and a single yarn count of 12,000 is used.

Fiber bundle [A-2]:

A continuous carbon fiber bundle (manufactured by ZOLTEK Corporation, "Panex 35 (registered trademark)") with a fiber diameter of 7.2 μm, a tensile modulus of 240 GPa, and a single yarn count of 50,000 was used.

Matrix resin [M-1]:

Using 100 parts by weight of vinyl ester resin (manufactured by Dow Chemical Co., Ltd., "Derakane (registered trademark) 790"), as a hardener, tertiary butyl peroxybenzoate (manufactured by Nippon Oil & Fat Co., Ltd., "PERBUTYL (registered trademark) (Trademark) Z'') 1 part by weight, magnesium oxide (manufactured by Kyowa Chemical Industry Co., Ltd., MgO#40) as a thickener, 4 parts by weight, zinc stearate as an internal release agent (Sakai Chemical Industry Co., Ltd.) Manufacture, SZ-2000) 2 parts by weight of the resin composite obtained by fully mixing and stirring.

[Classification of bundle aggregate [A], and calculation method of combined bundle aggregate [b] content rate]

A sample of 100 mm×100 mm was cut out from the fiber-reinforced resin molding material, and the sample was heated in a furnace at 600° C. for 1 hour to remove the resin. Next, from the resin-removed sample, use tweezers to take out 400 bundle-like aggregates [A], and classify them into split fiber bundle aggregates [a], bonded bundle aggregates [b], and bonded cut aggregates [ c].

Fiber splitting bundle assembly [a]: Among the partial fiber splitting fiber bundles, the thin bundles divided by the fiber splitting treatment performed are used as the fiber splitting bundle assembly [a].

Combined bundle assembly [b]: Among the partially divided fiber bundles, according to the undivided treatment section or the entangled part, the entangled accumulation part and other inter-bundle bonding factors, it can be judged as "the bundles are in a combined shape" As a combined bundle assembly [b]. In addition, in the present invention, the "beams in a shape that are joined to each other" means that when the bundle assembly [A] is lifted up with tweezers, at least two or more bundles of the bundle assembly [A] are simultaneously lifted, and Even if it vibrates slightly, it will not be separated into separate bundles.

Combined cutting aggregate [c]: In the partial fiber bundles, it can be judged that there are division marks in the undivided fiber bundles, the inter-bundle bonding factors such as the undivided fiber processing section, the entangled part, and the entangled accumulation part, or After cutting, it is divided into pieces according to the natural yarn breakage in the process, as a combined cutting assembly [c].

Furthermore, the content rate of the bonded bundle assembly [b] in the fiber-reinforced resin molding material was calculated from the total number of the bonded bundle assemblies [b] classified above.

[Evaluation method of mechanical properties]

Use mold No. 1 that can make flat plates. After placing the fiber-reinforced resin molding material in the center of mold No. 1 (with a filling rate of 50%), it is cured under the conditions of approximately 140°C x 5 minutes by a pressurizing press at a pressure of 10 MPa. A 300×400 mm flat plate was obtained. The long side direction of the flat plate is set to 0°, and from the obtained flat plate from the 0° and 90° directions, 5 test pieces of 100×25×1.6mm (10 pieces in total) are cut out, and according to JIS K7074 (1988) ) Carry out the measurement.

(Example 1)

Using a reel, the fiber bundle [A-1] is taken out at a constant speed of 10m/min and passed through a vibrating widening roller that vibrates in the axial direction at 5 Hz. After the widening treatment, it passes through a 20mm wide width restricting roller , To obtain a widened fiber bundle with a widening of 20 mm. For the obtained widened fiber bundle, a splitting treatment means was prepared in which an iron plate for splitting treatment having a protruding shape with a thickness of 0.2 mm, a width of 3 mm, and a height of 20 mm was arranged parallel to the width direction of the reinforcing fiber bundle at equal intervals of 5 mm. This fiber splitting processing means was intermittently inserted and removed with respect to the widened fiber bundle to obtain a partial split fiber bundle.

At this time, the fiber splitting processing means is for the widened fiber bundle moving at a constant speed of 10m/min. The fiber splitting processing means is pierced for 3 seconds to create a fiber splitting processing section. The fiber splitting processing means is removed for 0.2 seconds, and the stab is repeated again. Actions.

The obtained partially split fiber bundle is divided into 4 equal parts with respect to the width direction in the splitting treatment section, and at least one end of the at least one splitting treatment section has a single yarn entanglement. The entanglement accumulation part formed by the accumulation of the entanglement part. When making a 1500m partial fiber bundle, it has never caused wire breakage or entanglement. The twists of the fibers in the fiber bundle pass in the moving direction when the fiber splitting processing means is inserted and removed, and the fiber can be split with a stable width. deal with.

The obtained partial fiber bundle is set on the creel, and is rolled out from the end of the fiber bundle outside the bobbin, and the cutting knife is inclined at an angle of 15° with respect to the longitudinal direction of the fiber bundle. The rotary cutter is continuous To cut the fiber bundles to obtain a bundle of discontinuous reinforcing fibers [A]. At this time, the cutting interval is adjusted to 6.5mm in advance so that it can be cut into a fiber length of 25mm. In addition, the inserted part of the split fiber bundle is expanded to 20mm width when the part of the split fiber bundle is wound by the winding step or the fluff tension applied in the cutting step. The fiber bundle width W is 7mm.

After the above-mentioned cutting step, by dispersing the bundle-like aggregate [A] in a uniformly dispersed manner, a discontinuous fiber non-woven fabric with isotropic fiber orientation is obtained. The area density of the obtained discontinuous fiber nonwoven fabric was 1 kg/m ² .

Using a doctor blade, the matrix resin [M-1] was uniformly applied to two polypropylene release films to prepare two resin sheets. The discontinuous fiber nonwoven fabric obtained above is sandwiched by these two resin sheets, and the nonwoven fabric is impregnated with resin by a roller, thereby obtaining a sheet-like fiber-reinforced resin molding material. At this time, the amount of resin applied at the stage of preparing the resin sheet was adjusted so that the reinforcing fiber weight content of the fiber-reinforced resin molding material became 47%.

For the obtained fiber-reinforced resin molding material, the content rate of the combined bundle aggregate [b] was calculated based on the classification of the bundled aggregate [A] and the method for calculating the content of the combined bundle aggregate [b], and the result was 13%. In addition, based on the aforementioned method of evaluating mechanical properties, the fiber-reinforced resin molding material was molded and the mechanical properties were evaluated. A series of evaluation results obtained are shown in Table 1.

(Example 2)

The fiber bundle [A-2] is unwound at a constant speed of 10m/min using a winder and passes through a vibrating widening roll that vibrates in the axial direction at 10Hz. After the widening process, it passes through a 60mm wide width restricting roll. A widened fiber bundle with a widening of 60 mm was obtained. For the obtained widened fiber bundle, a splitting treatment means in which an iron flat plate for splitting treatment with a protruding shape is arranged in parallel with the width direction of the reinforcing fiber bundle at equal intervals of 3.5 mm to produce a partial split fiber bundle. The other systems were evaluated in the same manner as in Example 1. At this time, the obtained partial fiber bundle is divided into 17 equal parts with respect to the width direction in the fiber splitting treatment zone, and at least one end of at least one fiber splitting treatment zone has a single yarn The entanglement part of the entanglement is accumulated into the entanglement accumulation part. In addition, compared with the fiber bundle [A-1], the number of single yarns in the fiber bundle is larger, so the width W when the fiber bundle is cut is 20 mm. A series of evaluation results obtained are shown in Table 1.

(Example 3)

The cutting interval was adjusted to 3.2 mm so that the fiber length of the bundle assembly [A] was 12.5 mm, and the evaluation was performed in the same manner as in Example 2 except for this. A series of evaluation results obtained are shown in Table 1.

(Example 4)

The angle of inclination of the cutting blade of the rotary cutter and the cutting interval are adjusted so that the cutting angle of the fiber bundle is 30° and the fiber length is 12.5mm Except adjusting to 6.2 mm, it carried out similarly to Example 2, and evaluated. A series of evaluation results obtained are shown in Table 1.

(Example 5)

The inclination angle and the cutting interval of the cutting blade of the rotary cutter were adjusted to 8.8 mm so that the cutting angle of the fiber bundle was 45° and the fiber length was 12.5 mm, except for this, the same procedure as in Example 2 was carried out. And evaluate it. A series of evaluation results obtained are shown in Table 1.

(Example 6)

Set the ironing roller to maintain the widening width of the fiber bundle immediately before winding the partial fiber bundle so that the width W at the time of cutting the fiber bundle becomes 30mm, and adjust the partial fiber bundle The fiber bundle width was evaluated in the same manner as in Example 3 except for this. A series of evaluation results obtained are shown in Table 1.

(Example 7)

In order to make the width W when cutting the fiber bundles 45mm, immediately before winding the partial fiber bundles, an ironing machine to maintain the widening of the fiber bundles is installed to adjust the width of the partial fiber bundles, Except for this, it carried out similarly to Example 2, and evaluated. A series of evaluation results obtained are shown in Table 1.

(Example 8)

When the fiber bundle is inserted into the rotary cutter and unrolled, the paper tube around which the fiber bundle is wound is removed, and the fiber bundle is wound out in an inward drawing method from the end of the fiber bundle inside the bobbin. Except for this, it carried out similarly to Example 3, and evaluated. A series of evaluation results obtained are shown in Table 1.

(Comparative example 1)

When cutting part of the fiber bundle, use a rotary cutter with a cutting blade at an angle of 90° with respect to the longitudinal direction of the fiber bundle and a cutting interval of 25mm to obtain a bundle assembly [A]. The system was evaluated in the same manner as in Example 1. A series of evaluation results obtained are shown in Table 2.

(Comparative example 2)

When cutting part of the fiber bundle, use a rotary cutter with a cutting blade at an angle of 90° with respect to the longitudinal direction of the fiber bundle and a cutting interval of 25mm to obtain a bundle assembly [A]. The system was evaluated in the same manner as in Example 2. A series of evaluation results obtained are shown in Table 2.

(Comparative example 3)

The fiber bundle [A-2] was not subjected to fiber splitting treatment but was cut directly to obtain a bundle-shaped assembly [A], except that it was performed in the same manner as in Example 2 and evaluated. A series of evaluation results obtained are shown in Table 2.

Regarding Examples 1 to 8, it can be confirmed that they have both excellent mechanical properties (flexural strength, elastic coefficient) and low deviation. Regarding Examples 4 and 5, it was confirmed that by increasing the cutting angle, the stress concentration at the end of the fiber bundle became larger, and therefore the mechanical properties were lowered, but it was at a level that was not problematic. In addition, regarding Examples 3, 6, and 7, it was confirmed that by adjusting the width of the fiber bundle during cutting, the inter-bundle bonding factor of the undivided processing section, the entangled part, the entangled accumulation part, etc. can be subdivided, and the The improvement of the mechanical properties and the reduction of the deviation (for example, the reduction of the CV (Coefficient of Variation) value of the bending elastic coefficient) is significantly effective. Regarding Example 8, the bundle-like aggregate [A] obtained by cutting a part of the fiber bundle was collected in a small amount when spreading. When the fiber length was confirmed, it was also found that the fiber length did not match 12.5mm, but the ratio was small. , Which is essentially the grade of fiber length that can be judged to be cut into the target.

On the other hand, with regard to Comparative Examples 1 to 3, in Comparative Examples 1 and 2, it can be seen that the cutting angle of the fiber bundle is 90°. Therefore, the stress concentration at the end of the fiber bundle is concentrated and the bundle assembly is combined [ The content rate of b] is also high, and the mechanical properties decrease and the deviation increases. Also, in Comparative Example 3 Among them, it can be seen that since the fiber splitting treatment is not performed on the reinforcing fiber bundles, the content of the combined bundle assembly [b] is high, and similar to Comparative Examples 1 and 2, the mechanical properties decrease and the deviation increases.

[Industrial availability]

In particular, the present invention can provide a fiber-reinforced resin molding material that can be used for the production of various molded products that require high mechanical properties and reduction of the deviation of the mechanical properties.

31‧‧‧Partial split fiber bundle

32‧‧‧Fiber splitting processing section

33‧‧‧Undivided fiber processing section

34‧‧‧Cut surface

37‧‧‧ Bundle aggregates

Claims (6)

A fiber-reinforced resin molding material, which is a fiber-reinforced resin molding material comprising at least a bundle of discontinuous reinforcing fibers [A] and a matrix resin [M], characterized in that: the bundle [A] is Partially divided fiber bundles formed by alternately forming a splitting treatment section and an unsplit treatment section that are divided into a plurality of bundles along the longitudinal direction of a fiber bundle containing a plurality of single yarns, relative to the length of the fiber bundle In terms of the side direction, the angle θ (0°<θ<90°) is cut so that the cutting surface extends through the splitting treatment section and the unsplit treatment section. Such as the fiber-reinforced resin molding material of claim 1, which is in the partial fiber splitting fiber bundle, and at least one end portion of the fiber splitting treatment section forms the entangled portion of the single yarn entangled, and/or the The entanglement accumulation part is accumulated by the entanglement part. The fiber-reinforced resin molding material of claim 1, wherein the bundle-like aggregate [A] includes at least one of the following aggregates: split fiber bundle aggregates divided into arbitrary bundle branches by fiber splitting treatment [ a]; By the undivided processing section, and/or the entangled part, and/or the entangled accumulation part, the combined bundle assembly in which the single yarns of the fiber bundle are combined with each other [b]; and the undivided fiber The processing section, and/or the entangled portion, and/or the entangled accumulation portion intersects the cutting surface when cutting the partial fiber bundle, and in the intersection portion, the single yarns of the fiber bundle are combined by each other Combination of cutting and cutting aggregates [c]. The fiber-reinforced resin molding material of claim 3, wherein in the bundle-shaped aggregate [A], the content of the bound bundle aggregate [b] is in the range of 0-15%. A method for manufacturing a fiber-reinforced resin molding material, which is a method for manufacturing a fiber-reinforced resin molding material as claimed in any one of claims 1 to 4, characterized in that the bundle assembly [A] is obtained The following formula (1) is used to cut this part of the split fiber bundle; W. cosθ/D≧3． . . (1) W: The width of the fiber bundle when a part of the split fiber bundle is cut. D: The interval between the cut surfaces of the bundle assembly [A]. For example, the method for manufacturing a fiber-reinforced resin molding material of claim 5 is to perform a widening process on the partial fiber-divided fiber bundle at any point before cutting the partial fiber-divided fiber bundle.

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